Wine By the Numbers
Aug 17, 2015
How many grapes does it take to fill a 750ml bottle of wine? The answer is about 600 to 800 grapes or about 2.75 pounds, depending on the grape variety.
Here are some more fun numbers. One ton of grapes yields approximately 150 gallons of wine. A wine barrel will hold 59 of these gallons of wine which yields 24.6 cases which equates to 295 bottles. For practical purposes, we will round this last number up to 300 bottles of wine per barrel. These numbers are the easy ones because they do not vary. What does vary is the yield from the vineyard itself, i.e., how many barrels or bottles of wine do we get per acre of vineyard. This yield is expressed in tons per acre in the U.S. In Europe and just about everywhere else in the world, yield is expressed in hectoliters per hectare (HL/HA). A hectoliter is 100 liters (26.42 gallons) and a hectare is 10,000 square meters (2.47 acres). For obvious reasons, we will stick to tons per acre! However, for those of you who are really curious, there is a conversion factor. One ton per acre is approximately 17.5 HL/HA.
Vineyard yields are dependent on many factors, some of which the grower and/or wine maker can control and some that they cannot. These factors include geography (hillside or valley floor), climate, weather, soil type, vine density, vine age, irrigation, use of pesticides and fertilizer, type of grape, and sometimes just good or bad luck. Yields can vary from less than .5 tons per acre in a hot, high, unirrigated, old vine Spanish vineyard to over 20 tons per acre of irrigated Pedro Jimenez grapes in Australia that are used for the production of bulk, fortified wines. It's not a stretch of the imagination to assume that there will be a difference in quality and price between these two extremes.
More typical yields for quality wines are in the 5 tons per acre or less range. Appellation laws in France and Italy actually specify maximum yields. For example, the maximum yield in Bordeaux is 55 HL/HA or a little over 3 tons per acre. There are no such laws in the U.S. and typical yields can reach 4 to 5 tons per acre. Even these yields are considered high in some cases, so it's not unusual for viticulturists and/or winemakers to thin their grapevines and drop from 1/3 to ½ of the grape bunches on the ground to reduce yield. It's quite a shock to see a vineyard with all these grape bunches on the ground.
There is a reason that appellation laws limit maximum yields and growers and winemakers sometimes take drastic actions on their own to limit yields. There is a broad consensus that grape and wine quality are inversely proportional to yield, i.e., the lower the yield, the higher the quality and vice versa. The idea being that fewer bunches per vine means more water, nutrients, and minerals available for the grapes that remain.
Limiting yield may improve quality, but it also has economic consequences. All those grape bunches on the ground represent foregone revenue. Thus, one of the many factors growers and winemakers have to weigh is quantity (revenue) vs quality. Less grapes equals less production to spread the costs over which results in increased cost to you the consumer. This in a nutshell (or a grape skin) is the difference between bulk wine producers and quality wine producers. Which would you expect to be of higher quality and cost more?
Now that we have talked about vineyard yields and why they can vary, let's look at some more numbers. For our purposes, we will assume a yield of 2 tons per acre which is generally considered low yield. For additional context, let's talk about how big an acre really is. An acre is 43,650 square feet. This sounds like a lot, but if it were a square plot, it would be 209 feet by 209 feet, which doesn't sound quite as large. Using a yield of 2 tons per acre also makes it easier to estimate the numbers for smaller or larger yields such as 1 ton per acre, 4 tons per acre, etc. Finally, remember that these numbers are just approximations. They will vary depending on the type of grape and other factors.
2 tons/acre will yield the following:
Gallons of wine 300
For a 209 foot by 209 foot plot, 1500 bottles seems like quite a lot. Double the yield and you are up to 3000 bottles or 250 cases. If you have 40 acres of vineyards, you are now up to 10,000 cases. These figures really illustrate the advantage of economy of scale. There is a much larger base over which to spread your costs. This is another reason why wines from small producers, say in Virginia, tend to be more expensive than their larger brethren.
The next time you open a bottle of wine, this should give you a better understanding of what went into filling it and why there can be such large differences in its cost.